Counterboring tool



:- portion of a bolt, threaded into Patentecl July 10, 1923.

UNITED T sTArs MICHIGAN, ACORPORATION OF JwKENGEL, or nn'rnorr, MICHIGAN, vnssrerlvons I -'.ro ECLIPSE INTERCHANGEABLE COUNTERBORE COMPANY, or DETROIT,

MICHIGAN;

. COUNTERBORING rooL.

,- Application filed December @1921.

T 0 all whom it may concern: 7

, v,Be it known that we, JOHN E. SMITH and Gnonen J. ,KENGEL, both citizens of the United States of America, residing at Detroit, in .the coiuity of Wayne and State of Michigan, have invented certain new and useful Improvements in Gounterbo-ring Tools, ofwhich the following is a specification,-reference being had therein to the accompanyingdrawings.

' This invention relates to counterboring tools and .the invention consists primarilyin a .provision forreadily withdrawing the end for securing a cutter to the holder in case said bolt becomes broken through overstraimand furthermore the invention consists in a novel interlocking relation between tool and holder, for establishing a drive.

In the drawings z- Figure 1 is a View of in elevation;

Figure 2 is an axial sectional view of the same;

Figure 3 is an end view of the tool holder;

Figure a1. is a view in side elevation of the portions of the cutter which is adapted to have driving and aligning engagement with the holder;

Figure 5 is a plan view of. said portions;

Figure 6 is a fragmentary sectional view corresponding to the lower portion of Figure 2 but showing a construction eliminating a pilot member.

In these views the reference character 1 designates a rotative tool holder having the usual tapered end portion 1 for engaging a corresponding socket element (not shown). 2 is a counterboring cutter having the usual end teeth 2. 3 is a bolt functioning to secure the cutter 2 to the holder 1 andhaving a head 3 seating centrally against the cutting face of the cutter 2 and functioning as a pilot member. Instead of directly engaging a shank of the bolt 3 with an axially tapped hole in the holder 1, as is common in the art, the invention provides an exteriorly and interiorly threaded bushing 4 which is engaged in an axially tapped opening 5 of the holder and the shank of the bolt fits into said bushing, engaging the interior threads thereof. Thus in case of the bolt breaking the improved tool a tool holder key 6 and engageable Serial No. 522,234.

through any cause, the end portion of said bolt engaging in the holder may be readily removed by taking out said bushing. The bushing is adapted for ready removal by forming diametrically opposed notches 6, for engagement by a suitable spanner wrench. l/Vhen the bolt 3 breaks the fracture usually occurs in close proximity t'o the holder 1, so that the projecting portion of said bolt-is not ofsufiicient extent to be readily gripped for the purpose of removal. Under such conditions, the broken end portion of the bolt presents a problem which hasheretoforebeen solved only at considerable expense. The use of the described bush: mg however permits a broken'piece of bolt to be removed without dificulty or loss of tune.

A further feature ofthe present invention is a'novel means for establishing a drive 3 from the tool holder to the cutter." Thus upon its holder-engaging'extremity the cutter is formed with a convex key 6 having two opposed plain faces 6 This key is snugly engageable in acorrespondingly shaped socket 7 milled in the end face of the holder 1. While key and socket drive 0011-.

end face of the cutter. This permits the cutter to be seated very firmly and accurate- 7 i i ly upon the holder and furthermore the holder (or cutter) is not weakened by extending a groove or channel entirely across the end face -thereof.

To center the cutter perfectly with respect to the holder there is provided the cylindrical boss 8 centrally projecting from the snugly ina correspondingly shaped extension 9 of the socket 7. 1

An important advantage derived from the described construction lies in the fact that a variety of bushings 4, differing as regards their interior diameters may be employed 1, thus permitting variwith a given holder ous diameters of bolts 3 to be employed with the holder, and increasing the range of utility of the tool through this interchangeability.

The described construction furthermore presents a decided advantage over the majority of counterboring tools, in that the drive to the cutter is established in rela tively close proximity to the cutting teeth, which relation is conducive to strength. It is a further feature of the described construction that the driving means formed by the key 6 is practically independent of the centering boss 8.

\Vhile the described construction is peculiarly advantageous as applied to a counterboring tool, it will be understood that the invention is not limited in its scope of such an application.

When the head of the bolt 3 is not required to function as a pilot said head may be countersunk below the teeth of the cutter as indicated at 3 in Figure 6.

hat We claim as our invention is 1. In a boring tool, the combination With a cutter and a holder therefor having abutting end faces, of a drive key projecting from said end face of one of said members, having a pair of opposed plane faces substantially parallel to the axis of said member, the other member being formed with a correspondingly shaped socket engaged by said key and having a lesser diametrical extent than said member, of a cylindrical boss pro- 1ecting from said key and axially engaging the socketed member to relatively center the two members.

2. In a boring tool, the combination with a cutter and a holder therefor, said cutter and holder having abutting end faces, of a convex key projecting from one of said end faces, said key having a pair of opposed plane faces substantially parallel to the axis of said member and having a cylindrical boss projecting from said key, the other of said members having a socket snugly receiving said key and extent than that of said member, said socket having a cylindrical extension for receiving said boss for relatively centering the cutter and holder and means extending centrally through the cutter engaging the holder to secure the cutter thereupon.

3. In a boring tool, the combination with a cutter and a holder therefor having abutting end faces, of a drive key projecting from said end face of one of said members, the other member being formed-With a correspondingly shapedsocket engaged, by said key, and a cylindrical boss projecting from said key and concentrically engaging the socketed member to relatively center the two members.

In testimony whereof we affix our signatures.

JOHN E. SMITH. GEORGE J. KENGEL.

having a lesser dia-metrical 

